Cutterhead with replaceable inserts

ABSTRACT

A rotary cutting tool for cutting material surfaces such as wood or metal. The cutting edges comprise a plurality of replaceable inserts held in place by an improved clamping mechanism. In an extended length version such as would be used for finishing a wide surface, a plurality of straight inserts are mounted side by side in an approximation of a helical pattern.

United States Patent Vora Jan. 15, 11974 CUTTERHEAD WITH REPLACEABLE3,588,976 6/1971 Dupuis et al 29/105 x INSERTS I 3,688,367 9/1972Bennett 29/105 1 2,600,651 6/1952 Hogg et a]. 408/197 x [75] Inventor:Prabodh Mohanlal Vora, Beloit,

Wis. FOREIGN PATENTS OR APPLICATIONS 1,369,473 7/1963 France 144 218[731 Ass'gnee' 5 Black I' Deck" 2,446,490 5/1947 Switzerland 29/105 gCompany 528,883 4/1957 France.., .1 29/105 [22] Filed: Feb.-l8, 1972Primary Examiner-Andrew R. Juhasz [211 App} No 227 473 AssistantExaminer-W. R. Briggs [52] U.S. Cl 144/221, 29/105 R, 144/230 [57]ABSTRCT [51] Int. Cl B27g 13/04 A rotary cumng tool 9 cuttmg mammalSurfaces Such [58] Field 61 Search 29/105 R, 108; Wood or metal TheCutting edges comprise a P 408/197; 144/218, 221, 230 rality ofreplaceable inserts held in place by an improved clamping mechanism. Inan extended length l 56] References Cited version such as would be usedfor finishing a wide sursh111e r 29 105 face, a plurality of straightinserts are mounted side by side in an approximation of a helicalpattern.

' 2 Claims, 6 Drawing Figures PAIENTEBJAH I 5mm 5" 785,417

sum 1 (If 2 for a surface finishing and shaping machine and particularlyrealtes to improvements in the manner of locating cutting edges in thecutterhead.

BACKGROUND Previously known rotary cutterhead include a generallycircular or cylindrical body adapted to be mounted on a rotary shaft.The head also includes a plurality of cutting edges mounted on the bodyand extending in a suitable configuration to perform the desired cuttingoperation.

The cutterheads taught by the prior art have attempted to achieve avariety of objectives including more efficient cutting, improved finishon the workpiece, simplified and less expensive clamping mechanisms and,more recently, reduced noise. However, the various cutterhead systemspreviously proposed have been found to fail in meeting one or more ofthese objectives. For example, many previous clamping mechanisms requirethe presence of deep pockets in the assembled cutter, thus causing loudsiren noise which may be harmful to the operator. Other clmapingmechanisms hav been subject to failure, thus permitting the release ofthe cutting elements with consequent damage or injury; still othersrequire complex and difficult alinement procedures to accuratelyposition the cutting edges.

A further difficulty has been encountered in the particular field ofplaner heads of extended length. In this operation, it has been foundthat the use of a spiral blade positioned along a helix on thecutterhead provides substantially improved cutting together with reducednoise. However, the provision of extended spiral blades, particularly ofcarbide, is expensive. Approximations which have previously beenattempted have either failed to be sufficiently close to a helix toprovide the desired advantages or have produced other difficulties whichmay be even more undesirable. For example,

a simple shear-cut slot design is limited to a relatively short lengthbecause the hook angle or radial rake angle increases with increase inbody length. It has also been suggested to produce such heads insections, any numberof which may be mounted on a shaft but these cuttershave been found to be insufficiently rigid and subject to run-outinaccuracies.

OBJECTIVES OF THE PRESENT INVENTION The primary purpose of the presentinvention is the provision of an improved rotary cutterheadincorporating a simple, accurate blade clamping mechanism which avoidsthe hazards, complexities and noise problems of the prior art. Inaddition, it is a primary purpose of this invention to provide anextended length cutterhead construction which can readily be produced inany desired length without encountering the difficulties of the priorart.

Accordingly, it is an object of the present invention to provide aunique clamping mechanism for cutting edges in a rotary cutterhead whichprovides accurate rigid and safe operation without undue cost.

It is another object of this invention to provide an improved clampingmechanism for cutting edges in a rotary cutterhead which enables simple,accurate cutting edge renewal.

It is also an object of this invention to provide an improved rotarycutterhead which defines a substantially helical cutting edge by meansof a plurality of straight cutting inserts.

It is also an object of this invention to provide an improved rotarycutterhead which is substantially less noisy in operation than previouscutterheads.

Further objects and advantages of this invention will become apparent asthe description and illustration thereof proceed.

IN THE DRAWINGS FIG. l is a perspective view of a rotary cutterhead inaccord with the present invention;

FIG. 2 is a cross sectional view taken along the lines 22 of FIG. 1;

FIG. 3 is a cross sectional view taken along the lines 3-3 of FIG. 2; v

FIG. 1 is a perspective view of an elongated cutterhead constructed inaccord with the present invention;

FIG. 5 is a perspective view of the cutter body of FIG. 4 shown at anintermediate stage of manufacture; and

FIG. 6 is a schematic view illustrating the principle used inconstructing the cutterhead of FIG. 4.

In FIG. I, a rotary cutterhead in accord with the present invention isillustrated which includes a cutter body 10. The body 10 is adapted tobe mounted on a dirve shaft, not shown, by means including nut 11 inaccord with conventional practice. Other types of drive mechanisms mightbe substituted therefor. In the circular circumference of the cutterbody 10, a plurality of slots 12 are provided, each of which is adaptedto receive a cutting blade 13 and a blade-locking wedge or gib 14. Inthe illustrated head, the axial length of the cutting edge may forexample be approximately 2 inches.

FIG. 2 illustrates a cross sectional view through a slotted portion ofthe cutter and shows in detail the relative location of the gib andblade in the slot 12, while FIG. 3 illustrates the full width of theblade in the head. The blade 13 may be fabricated from any suitablematerial such as high speed steel, butthe present invention isparticularly well suited for use with carbide blades of the type wellknown in the industry. The particular blade 13 used in this instance isprovided with a circular hole 15, an elongated hole 16 and two cuttingedges 17, 18 which are very precisely located during manufacture of theblade with respect. to the holes 15, 16. The blade is mounted in placevia holes 15, 16 on cams 19, 20 which are eccentrically mounted on theends of screws 21, 22. The blade is retained in place by the gib 14which is provided with a pair of suitable apertures 23. A pair of screws24, shown in FIG. 1, are threaded into sockets 25 in the cutterhead 10.

This manner of locating the blade and fixing it in place is a particularfeatureof the present invention. Specifically, the provision of holes15, 16 and the precise location of cutting edges 17, 18 relative tothese holes permits very accurate and repeatable positioning of theblades in the cutterhead by means of the cams 19, 20. The cams aresmaller in diameter than the holes 15, 16, and as screws 21, 22 areadjusted, the cams raise and lower the respective ends of the bladeuntil it is accurately positioned. Once the edge 17 is accuratelyaligned, lock screws 26 are threaded into the bores 27 to secure thescrews 21, 22 against further movement. Thereafter, accurate edgerenewal may be accomplished by simply removing the gibs 14 and invertingthe blade or substituting a new blade once both edges have been used.Extremely accurate alignment of the blade is made possible by virtue ofthe use of two locating points 15, 16. In addition, the accuracy of thisconstruction is substantially increased in comparison to prior art usageof cam pins since the cutting force and the gib action both are in adirection to seat the blade tightly on the cams rather than lift it awayfrom the cams. Also it is noted that the adjusting surfaces act directlyon the blade. This increases the accuracy of edge location and, whenwrecks do occur, only the blade must be replaced rather than a complexlocating system.

Several other advantages also accrue to this construction; Specifically,the blades are retained securely within the cutter by the cams eventhough the gib should loosen slightly. Thus, the operator is protectedagainst the danger of a blade flying out of the cutter at high speed. Afurther advantage of this construction is the fact that the pocketspreviously referred to which produce siren noise during cutter operationare substantially reduced and may be almost completely eliminated bysimply placing a piece of tape in the relieved surface of the gib afterthe assembly has been completed.

A less obvious advantage of the present construction is that thisconstruction, in contrast to many prior art arrangements, includesvertically arranged sockets 23 and 25 which require that the gib 14 becompletely removed from the slot before the blade can be changed orinverted. This forces the operator to remove chips, etc. which might bepresent in the area of the blade. The possibility that he will simplyslip a new blade into a narrow opening over a sufficient quantity ofchips, dust, etc. to subsequently cause blade breakage when the gib istightened, as is permitted by prior art arrangements, is eliminated.Also, by virtue of this construction, the gib l4 and screws 24 cannot beput in place unless the blade has been properly mounted on cams 19 and20. Again, this reduces the possibility of blade breakage which mightoccur if the operator were to attempt to force the blade into place bytightening the gib with the blade slightly misaligned. However, the mostsignificant advantage of this construction is that of quick andinexpensive blade change without need for readjustment of the locatingmechanism and without any need for regrinding the blade edges afterreplacement or inversion.

FIG. 4 illustrates an elongated rotary cutterhead in accord with thepresent invention, for example such as might be used in a planingoperation on a wide wooden surface. As can be seen in this view, thecutterhead 30 includes a plurality of slots 12, all but one of whichcontains a plurality of blades 13 and gibs or wedges 14. The upper slothas been left empty to show the sockets 25 and bores 27. Each blade-gibcombination is mounted in exactly the same manner as has been previouslydescribed; thus, the advantages noted previously for thesingle-blade-width cutter also pertains to the cutter shown in FIG. 4.lt is also noted that the blades in alternate rows are mounted instaggered relationship so that the small space left uncut betweenadjacent blades in each row is cut by the blade edge at thecorresponding axial location in the next row. (The space shown in FIG. 4is exaggerated for clarity.) Also, this arrangement enables a cutterheadof any desired length to be manufactured even though the blades are ofstandardized length. This arises from the fact that the relativeposition of the blades in each row can be controlled during manufactureso as to adjust the overall length to any selected value.

The cutterhead of FIG. 4 also embodies a further significant feature ofthis invention, namely, an improvement in the construction of a helicalcutter edge. It is well known in the cutting art that'severalimprovements in the efficiency, cut quality and noise level of a cuttingoperation can be achieved by providing a helical cutting edge on thecutterhead, rather than the straight, paraxial edge which has previouslybeen used. However, as noted in the introductory portion, difficultieshave been encountered with the several known methods of attempting toprovide such a cutting edge.

In accord with the present invention, a series of straight blades of thetype shown in FIG. 3 are mounted in suitable slots milled into thesurface of the cutterhead so as to approximate the desired helix. Thus,the necessity of twisting a blade into a helical shape is avoided; atthe same time, the manner of approximating the helix is substantiallyimproved as compared to the techniques previously attempted.

The specific construction by which this is achieved is illustrated inFIGS. 5 and 6. FIG. 6 shows a true helix 31 as it would appear on thesurface of the cylindrical body 30. Superimposed on this helix 31 is anapproximation 32 formed by a series of straight lines. As appears fromthis illustration, the two lines are very much the same. In fact, thelength of the straight line segments in FIG. 6 has been exaggerated; theactual situation on a cutter body is even closer to the true helix.

FIG. 5 shows a portion of the cutter body 30 including only the firstthree segments; in essence, the segmental regions 33, 34 and 35 arestraight line slots corresponding to the segments of approximation 32.The segments are produced so as to approximate a helical slot in thesame manner as line 32 approximates line 31. In the view of FIG. 5, twosuccessive milling operations of this type have been performed. In thefirst, a straight end mill has entered end 36 and produced the flatblade-side 37 of the segment 33. This flat end is sufficiently long toreceive a blade 13. The end of the first pass is indicated by thecutterhead radius 38 and cutter sweep 39. The mill is then withdrawn andthe cutterhead is rotated relative to the mill to the position requiredfor the next straight segment. The mill is then moved into the body andtraversed to form the flat 40 in segment 34. This operation is continuedto the end of the body.

Because each of the individual segments are straight and because theyrun at an axial rake angle across the cutter, an adjustment in height isnecessary to accommodate the blade to the changing raidal distance tothe top of the slot. This is accomplished by varying the depth of thecut slightly across the length of each straight segment and byappropriately grinding the cutter edge of the blade. In fact, the blade13 shown in FIG. 3 is shaped for this purpose. The varying depth of theend mill from one end of each straight segment to the other isillustrated by the appearance of radius 38 in FIG. 5.

After the series of straight segments on the blade-side 33 have beencompleted, a second cutter is introduced at the gib-face side of theslot. This cutter is also moved in a series of staggered straight linesegments in the manner shown in FIG. 6 to produce a similarapproximation of a helix comprising the flats 41, 42, etc. Because bothsides of the slot 12 consist of a series of straight line segments, boththe blade and the gib can be fabricated with flat surfaces and simplydropped in place in the respective straight segments, thus eliminatingthe need to fabricate these parts with matched heliea] or curvedsurfaces. After milling the slots in this manner, or by other suitablemeans, the apertures for the gib-mounting bolts and for theblade-locating screws are drilled and tapped and these respective partsare mounted, each in a manner described in connection with FIGS. 1-3.

It can be seen from the foregoing description and drawings that acutterhead construction in accord with the present invention providesnumerous advantages as compared to the constructions previouslyavailable. The extended length cutterhead illustrated in FIG. 4 and 5provides a cutting edge which is a very close approximation to a truehelix without encountering the difficulties of twisting carbide or ofmatching widely staggered or independently mounted blade edges. Inaddition, in both the extended length and single element embodiments, animproved blade clamping system is provided which enables accuratepositioning of the locating members to permit simple replacement of theblades. During placement of the blade and during operation of thecutter, the forces acting on the blade are such as to retain the bladeprecisely on the locating surfaces of the cam screws, thus providingmaximum assurance that the accuracy will be maintained.

As an alternative embodiment, it is noted that the blade locating pointsmight also comprise a pair of straight edges provided on the backsurface of the blade, one of which would contactan appropriate locatingsurface in the same manner as illustrated in FlGS. 2 and 3. However,this embodiment does not retain the added safety provided by theextension of the cams through openings in the blade which prevents theblade from being thrown outof the head. Therefore, the illustratedembodiment is a significant improve ment and is preferred.

A further advantage of the construction of this invention is a functionof the small space left between adjacent blades in a given helical row.This assists in chip breakage and prevents the formation of chips aswide as the cutting blade. Thus, this is an additional feature of thesubject invention.

Although a limited selection of embodiments of this invention have beenillustrated and described in the foregoing specification, it will beclearly understood by those skilled in the art that many changes andmodifications may be made therefrom without departing from the essentialconcept of this invention. For example, the described construction maybe adapted to a variety of cutterheads in both the metal and woodworking fields without sacrificing the essential features of thisinvention. Accordingly, it is intended that the appended claims coverall such changes and modifications as may fall within the true spiritand scope of this invention. I

I claim: I

l. A cutter head for rotary cutting machines comprising a cylindricalcutter body; a straight slot in said body, said slot being disposed atan angle to the axis of said body; a replaceable cutting blade in saidbody, said blade having an exposed first cutting edge extending abovethe cylindrical surface of said body; said blade including a secondcutting edge disposed within said body; wedge means in said slot forretaining said blade against one side of said slot, said wedge having anaperture therein; bolt means for securing said wedge in said cutterbody; and a plurality of independently adjustable cam means spaced insaid cutter body in a direction parallel to said exposed first cuttingedge, each of said cam means comprising screw threaded means mounted insaid cutter body and having an eccentric projection extending into saidslot; said blade including apertures for receiving said eccentricprojections.

2. A cutter head for rotary cutting machines comprising a substantiallycylindrical body, a plurality of slots in the surface of said body; eachof said slots comprising a plurality of straight line segments, saidsegments being angled relative to adjacent segments so that each of saidslots approximates a helix; a plurality of blades, each of said bladescomprising a straight cutting edge, said cutting edges having a lengthequal to that of said segments; wedge means for mounting each of saidblades in said segments; and a plurality of independently adjustableeccentric projections extending from said cutter body into engagementwith each of said blades whereby each of said blades has at least twoindependent eccentric projections associated therewith for adjustment ofsaid cutting edge.

1. A cutter head for rotary cutting machines comprising a cylindricalcutter body; a straight slot in said body, said slot being disposed atan angle to the axis of said body; a replaceable cutting blade in saidbody, said blade having an exposed first cutting edge extending abovethe cylindrical surface of said body; said blade including a secondcutting edge disposed within said body; wedge means in said slot forretaining said blade against one side of said slot, said wedge having anaperture therein; bolt means for securing said wedge in said cutterbody; and a plurality of independently adjustable cam means spaced insaid cutter body in a direction parallel to said exposed first cuttingedge, each of said cam means comprising screw threaded means mounted insaid cutter body and having an eccentric projection extending into saidslot; said blade including apertures for receiving said eccentricprojections.
 2. A cutter head for rotary cutting machines comprising asubstantially cylindrical body, a plurality of slots in the surface ofsaid body; each of said slots comprising a plurality of straight linesegments, said segments being angled relative to adjacent segments sothat each of said slots approximates a helix; a plurality of blades,each of said blades comprising a straight cutting edge, said cuttingedges having a length equal to that of said segments; wedge means formounting each of said blades in said segments; and a plurality ofindependently adjustable eccentric projections extending from saidcutter body into engagement with each of said blades whereby each ofsaid blades has at least two independent eccentric projectionsassociated therewith for adjustment of said cutting edge.